Question

If a current carrying circular loop is suspended in a uniform magnetic field \(\vec{B}\), then

• A. a couple will act on the loop
• B. the loop will start to rotate
• C. areal vector of the loop will be set in the direction of $\vec{B}$
• D. areal vector of the loop will be perpendicular to the direction of $\vec{B}$
• E. loop will be deflected away from the field $\vec{B}$

Hint:

Magnetic dipole in field: - Always aligns along magnetic field direction - Similar to electric dipole in electric field

Answer 1

The Correct Option is C

Concept: A current loop in a magnetic field experiences torque: \[ \vec{\tau} = \vec{m} \times \vec{B} \] where magnetic moment: \[ \vec{m} = IA\hat{n} \]

Step 1: Understand torque effect.
Torque tends to align $\vec{m}$ with $\vec{B}$.

Step 2: Relation with areal vector.
Areal vector $\hat{n}$ is along magnetic moment: \[ \vec{m} = IA\hat{n} \]

Step 3: Final alignment.
\[ \hat{n} \parallel \vec{B} \]